1. Field of the Invention
The present invention relates generally to a type of fuel cell system. More particularly, the present invention relates to a type of fuel cell system that temporarily shuts down power generation under a low load.
2. Description of the Related Art
In a vehicle carrying a conventional fuel cell system, when all of the following conditions are met, that is, when the vehicle speed is lower than a prescribed speed, the output power of the motor for traveling and the output power of the motor for driving the air compressor for driving the fuel cell are lower than respective prescribed motor output powers, the brake is ON, and the voltage between terminals of the accumulator is higher than a prescribed voltage, then feeding of the reaction gases to the fuel cell is stopped, and power generation of the fuel cell is temporarily shut down. That is, an idle stop operation is performed.
Japanese Kokai Patent Application No. 2001-359204 discloses this type of conventional fuel cell system. However, the fuel cell of this type can experience problems relating to the durability of the solid-state polymer fuel cell. That is, when power generation of the fuel cell is shut down, the voltage of the fuel cell stack rises, and the fuel cell stack deteriorates. This phenomenon is considered undesirable.